Preparation of halogenated acetylenic alcohols



ard e'ven in the case of United States Patent 2,989,568 PREPARATION OF HALOGENATED ACETYLENIC ALCOHOLS James P. Russell, North Bergen, and James F. Vitcha,

New Providence, NJ., assignors to Air Reduction Company, Incorporated, New York, N. a corporation of wherein X is chlorine or bromine and R and R are hydrogen, a lower alkyl radical, i.e. an alkyl radical containing 1 to 5 carbon atoms, an alicyclic radical, such as cyclohexyl, or the phenyl radical, with R and R being selected in such manner that the sum of the carbon atoms of R and R is at most seven.

Attempts have been made to prepare halogenated acetylenic alcohols of the type indicated by the aboveformula by reacting the corresponding acetylenic alcohol with the appropriate alkali metal hypohalite, e.g. sodium hypochlorite. Extreme difllculty has been encountered, however, by reason of the fact that when the prior art processes have been followed, highly explosive intermediates or by-products are produced which render the operation extremely hazardous and delicate. This problem is particularly acute in connection with the preparation of chlorinated acetylenic alcohols such as 1-chloro-3-methyll-butyn-3-ol. Attempts have been made to avoid these hazards by using very low temperatures but such attempts have been generally uneconomical and have required excessive reaction times.

It is an object of this invention to provide an improved process for preparing halogenated acetylenic alcohols, particularly the chlorinated acetylenic alcohols, which avoids the explosion hazard heretofore encountered.

It is a further object of the invention to provide a process of the character indicated which makes possible the smooth, elficient and safe production of halogenated acetylenic alcohols of high purity.

In accordance with the invention, halogenated acetylenic alcohols are directly prepared from the corresponding acetylenic alcohol by treating an acetylenic alcohol of the formula wherein R and R have the meanings given above, with an alkali metal hypohalite at atmospheric pressure in the presence of a lower alkyl ether, i.e. an alkyl ether having an alkyl group of 1. to 7 carbon atoms. It is a feature of the invention that the presence of the lower alkyl ether eifectively eliminates the explosion hazthe preparation of chlorinated acetylenic alcohols.

It is another feature of the invention that halogenated acetylenic alcohols of high purity are directly produced.

Other objects and featuresof the invention will become apparent as the description thereof proceeds.

The lower alkyl ethers which are employed, in accordance with the invention, are characterized by the formula R--O-R" wherein R and R' are the same or different alkyl groups containing 1 to 5 carbon atoms, inclu- 'ethynyl cyclohexanol, and 3-phe'nyl-l-butyn-3-ol.

2 sive, and have a boiling point at atmospheric pressure above 35 C. Examples of alkyl ethers suitable for use in accordance with this invention are di-ethyl ether, diisopropyl ether, ethyl isopr'opyl ether, di-n-butyl ether, methyl-n-butyl ether, di-amyl ether, ethyl-amyl ether, and butyl-arnyl ether.

The alkali metal hypohalite which is employed corresponds to the halogen to be introduced into the acetylenic alcohol. In preparing a chloro-acetylenic alcohol, for example, sodium hypochlorite or potassium hypochlorite are advantageously employed and in preparing bromo acetylenic alcohols, the corresponding bromo alkali metal hypohalites, e.g. sodium hypobromite and potassium hypobromite are utilized. The alkali metal hypohalite-j-is suitably employed in aqueous a concentration of 8 to 15% are particularly effective. Advantageously, the alkali metal hypohalite is prepared in situ in the reaction vessel before the ether and the acet .ylenic alcohol are introduced. Thus, in a typical operation, an alkali metal hydroxide, e.g. sodium hydroxide or potassium hydroxide, is dissolved in sufficient water to provide the concentration of alkalimetal hypohalite indicated above and the halogen, i.e. chlorine or bromine, is then gradually introduced into the aqueous alkaline solution substantially at room temperature or slightly above, until the desired concentration of hypohalite. has been formed. For example, cooling of the reaction mixture is eifected in order to keep the temperature from ex"- ceeding about 36 C. For best results, a ratio of alkali metal hydroxide to hypohalite of 1.5-1.7 to l is desirable although a lower or higher amount of .alkali metal hydroxide may be used and the ratio of alkali metal hydroxideto hypohalite may vary, for example, from 0.25 :1

\As previously indicated, the acetylenic alcohols used to prepare halogenated alcohols in accordance with this invention have thepformula H Examples of such acetylenic alcohols are 3-methyl-1-butyn-3-ol, l-pentyn-B -Ol, 3-methyl-1-pentyn-3-ol, 4-methyll-pentyn-3-ol, l-he'xyn-3-ol, 3,5-dimethyl-l-hexyn-S-ol, In the foregoing acetylenic alcohols it will be seen that the sum of the carbon atoms in R and R is at most nine.

ardous and unsafe.

The quantity of alkali metal hypohalite may vary, but generally speaking the alkali metal hypohalite should be in 5 to 20% excess over the stoichiometric quantity required for the quantity of acetylenic alcohol employed. .Greater excesses may be used but no particular advantage is gained in so doing.

After the alkali metal hypohalite has been prepared in g the reaction vessel, or if it is separately prepared, after it has been charged to the vessel, flow of alkyl ether and acetylenic alcohol is begun. The ether and acetylenic alcohol is advantageously mixed and added dropw-ise at a rate such that a temperature of about 40 C. can be readily maintained.

The reaction may be carried out at a temperature as low as 30 C. but it has been found that somewhat more elevated temperatures are advantageous and prefe solution and solutions of 3 a temperature of 35 to'45 C. is employed. Temperatures in excess of 50 C. tend to cause decomposition of the hypohalite, causing foaming and loss of solution and, accordingly, 50 C. should not be exceeded and prefera- 4 were separated and the organiclayer carbonated with CO filtered through a A inch deep Filter-Col bed, and the ether flashed off by heating to a temperature of 100 C. The residual organic oil was fractionally distilled bly, the maximum temperature should be maintained not through a 25-plate column at 50 mm. l-chloro-3-methsubstantially above 40 C. Reaction is continued until yl-l-butyn-3-ol, B.P. 70/50 mm., n 1.4567, of 99.1% 9 5400% of the stoichiometric amount of hypohalite has purity was obtained in 98% yield. been consumed. Generally speaking, the reaction period increases with increasing molecular weight of the acety- EXAMPLE H lenic alcohol. For example, 3-methyl-lI-lbutyn-3-ol, 0 Preparation of 1-chlor0-3-methyl-I-pentyn-3-al pentyn-B-ol, 4-methyl-1-pentyn-3-ol, 3-me yl-l-pentyn- 01 and l-hexyn-3-ol react to form the corresponding 1 rag;iitfi iiggpegygigpgai salllliilstlttfiletegrggd 1tlll tes chloro compound in about 2 to 2.5 hours whereas 3,5-d1- of Example I was carried out there was Obtained Lchk} methyl-l-hexyn-B-ol requires a longer react1on time. The 3 th 1 1 t 3 1 B P 770/35 20 1 4615 hromo 'acetylenic alcohols are formed more rapidly and R52 y d f 94 reaction times of /2 hour or less are generally sufiicient. Q punty an m ayle 0 To facilitate reaction, the reaction mixture is contim EXAMPLE HI ousl stirred. The reaction vessel is suitably provi e with a cooling jacket, a reflux condenser, and inlets for Preparat'o" of a stirrer, a thermometer and the reactants. At the end In a five-liter, 4-necked flask provided with two gas of the reaction period, the contents of the reaction zone inlets, a reflux condenser, a dropping funnel, a thermome- P I into an aqueous layer d n Organic l y r, and ter, a stirrer, a gas outlet, a bubble counter, and a coolthe organic layer, which contains the halogenated acetying bath there were successively charged in the manner lenic alcohol product, is removed. The organic layer is described below the following: then neutralized, as with carbon dioxide, and filtered, and the filtrate distilled to remove the alkyl ether. The or- 450 (11 moles) ganic residual product is then fractionally distilled to re- H2O (dlstlned), 1350 moles) cover the product halogenated acetylenic alcohol. Bromine (anhydrous), 480 (3 molcs) I The invention will be more clearly understood from 3'methyl'l'pentyn'3'olr 294 (3 the following spe'cific examples which are given for illus- Ethyl ether, 150 moles) trativepurposes only and are not intended to be limitative The flask was first charged with water and flushed with of the mention P I nitrogen and the NaOH was then dissolved in the water. EXAM LE The alkaline solution was cooled to 25 C. Bromine Preparation of 1-chl0ro-3-methyl-1-butyn-3-0l was added with cooling and stirring, at a rfatg1 to conttlro he temperature at 33- -3. When all 0 e Br a In a five-l1ter, 4-necked flask provided with two gas t 2 inlets, a reflux condenser, a dropping funnel, athermomeq rate of i was Increased and the ter, a stirrer, a gas outlet, a bubble counter, and a coolmixture 0 at er i' if f g' ing hath there were successively charged in the manner i at a rate w w ept the milperature described b e] ow the following: 40 with moderate coolmg (10 minutes addition time). After the addition was complete, the cooling was discon- NaOH 450 g 1110168) tinned and used only if the temperature exceeded 40 C. H O (distilled), 1350 gms. (75 moles) The temperature fell normally to 35 C. within 20 minchlolille y 235 g 1110168) utes after the addition was complete. At this point stir- 3-methyl-l-butyn-3-ol, 252 gms. (3 moles) ring was stopped and the reaction mixture worked up as Ethyl ether, 150 cc. (1. 62 moles) follows. The flask was first charged with water and flushed with. The Whlch mulled We nitrogen and the NaOH was then dissolved in the water. Para/[ed and the layer farbonated The alkaline solution was cooled to C. Chlorine filtered through a /4 Int 2h deep Frlter-Cel bed, and the was passed in with cooling and stirring, at a rate to eon- 5 ether i off i to a P P of trol the temperature at when all of the C12 The residual organic 011 was fractionally distilled through had been added, the rate of stirring was increased and a zsplate colllmn at 3 'P the mixture of ether and 3-methyl-1-butyn-3-ol added 55 /3 P 0 14908 of 100% Punt) was dropwise, at a rate which kept the temperature at 38-40 obtained 98% C. with moderate cooling (1.5 hours addition time). 55 EXAMPLEIV After the addition was complete, the coohng was dlSCOlI- i d and used only if the temperature exceeded 40 In similar manner, other l-chloroand l-bromo-acety- Th temperature f ll normally to 5 C within two hours lemc alcohols are readily prepared using the procedure aft r h addition was complete, At this point stirring described in Examples I and III and the following table was Stopped and h reacticn mixture worked up as 1. tabulates the conditions and the results obtained in the lows. The organic and aqueous layers which formed preparation of representative compounds.

Add'n Total Tenp Percent Alcohol Product Time, Time, Yield Hrs. Hrs.

l-pentyn-S-ol 1-chloro-1-pentyn-3-ol-.- .75 1.75 40-45 86 4-methy1-1-pentyn-3-ol l-chlgrogl lrnethyl-l- 1.0 2.0 40 87.6 l-ethynyl cyelohexanol-l. 1-1;: h lo1 ietl:1tyhyl)cyclo- 1. 2. 75 35 8,5-dimethyl-1-hexynol-3. l-gzll lh r d-li-dimethyl-l- 0.25 18. 25 30 99 8-phenyl-1-bntyn-3-ol.. 1- ii 1ii r 3;- phenyl-l- 0.25 4.25 35 9a tl-methyl-l-pentyn-ii-ol... l-b iomomethyl-l- 0.12 0.3 as 94 pentyn-B-ol.

The purity of the above products was generally 98 to 100% and the physical characteristics of the products are tabulated below.

The compounds prepared by the above-described process are useful as corrosion stabilizers for chlorinated solvents such as trichloroethylene and as inhibitors in plating baths and for these purposes are suitably used in concentrations of about 1%.

It will be understood that various changes and modifications may be made in the process of this invention without departing from the scope of the invention as defined in the appended claims and it is intended, therefore, that all matter contained in the foregoing description shall be interpreted as illustrative only and not as limitative of the invention.

What we claim and desire to secure by Letters Patent 1. A process for the preparation of acetylnic alcohols of the formula R! R(|JCECX 5H wherein X is selected from the group consisting of chlorine and bromine and R and R are selected from the group consisting of hydrogen, a lower alkyl radical, and the phenyl radical which comprises treating an acetylenic alcohol of the formula with an alkali metal hypohalite selected from the group consisting of alkali metal hypochlorite and alkali metal hypobromite in the presence of an alkyl ether having an alkyl group of 1 to 7 carbon atoms at a temperature of 30 to C.

2. A process for the production of acetylenic alcohols of the formula wherein X is selected from the group consisting of chlorine and bromine and R and R are selected from the group consisting of hydrogen, a lower alkyl radical, and the phenyl radical which comprises treating an acetylenic alcohol of the formula R! l R-C-CECH with an alkali metal hypohalite selected from the group consisting of alkali metal hypochlorite and alkali metal hypobromite, said alkali metal hypohalite being present in 5 to 20% excess over the stoichiometric quantity required to react with the acetylenic alcohol in the presence of at least 0.6 mol of an alkyl ether having an alkyl group of 1 to 7 carbon atoms per mol of acetylenic alcohol at a temperature of 30 to 50 C.

3. A process as defined in claim 2, wherein the alcohol is 3-methyl-l-butyn-3-ol.

4. A process as defined in claim 2, wherein the alcohol is 3-methyl-1-pentyn-3-ol.

References Cited in the file of this patent UNITED STATES PATENTS 1,841,768 Straus et a1. Ian. 19, 1932 

1. A PROCESS FOR THE PREPARATION OF ACETYLNIC ALCOHOLS OF THE FORMULA 